This invention relates to electric routers and guidebushings utilized with such routers in order to form wood veneer or other inlays and recesses for such inlays.
Guidebushings and sleeves are used with electric routers to form inlays of wood veneer or other routable materials like Corian(copyright) and other brands of solid surface countertop materials and to form recesses in workpieces within which such inlays are positioned. Generally, such conventional guidebushings and sleeves are sized to provide an appropriate off-set for a specific routing cutter, such as a {fraction (1/16)}xe2x80x3, xe2x85x9xe2x80x3 or xc2xcxe2x80x3 diameter cutter. Sleeves are also available for use with larger cutters. Such conventional guidebushings and sleeves are used, for instance, by forming an inlay by using a particular cutter and a bushing in contact with a female template. Then the same template can be used with a sleeve larger in diameter than the guidebushing by an amount twice the diameter of the cutter. This offsets the position of the cutter relative to the same female pattern by the diameter of the cutter so that the recess will be equal in size to the inlay.
However, if the cutter is oversize, the recess will be oversize and the inlay will be undersize, with a poor fit as a result. If the router cutter cuts undersize, the opposite is true. The recess will then be too small and the inlay will be too large.
There is, therefore, a need for apparatus and techniques that can accommodate variations in cutter size and allow adjustment of the relative size of the inlay and recess within which it fits to permit control of the fit.
This invention provides components and techniques permitting adjustment of the relative size of an inlay and a recess for that inlay cut with an electric router. This permits accommodation of variations in cutter size and greater control of the inlay and recess cutting processes.
A guidebush holder is secured to a router base at least reasonably concentric with the router collet. A guidebushing is secured in the holder in a manner permitting the position of the guidebushing to be adjustable along the axis of rotation of the collet. For instance, the holder maybe internally threaded to receive an externally threaded guidebushing that engages the holder internal thread and is selectively positionable along the axis of the router collet by rotation and consequent travel of the guidebush along the threaded inside of the holder. The guidebush has a protruding cylindrical bushing concentric with the router collet and through which a router cutter protrudes during use. Router position is controlled during formation of an inlay by contact between the outer wall of the guidebushing and a female template.
A guidebush sleeve having an appropriate nominal diameter is then slid over the cylindrical guidebushing and secured in place on that bushing by cooperation between an O-ring positioned in an internal annular groove in the sleeve and a recess in the upper portion of the guidebushing wall or other wall structure suitable for capturing the O-ring. The guidebushing sleeve is externally tapered so that the effective diameter of the guidebushing sleeve in contact with a template is a function, in part, of the position of the sleeve along the axis of the router collet, which position is adjustable by screwing the guidebush into or out of the holder. The smaller diameter portion of the sleeve is the portion most distant from the router collet. The nominal diameter of the guidebushing sleeve should be greater than the guidebushing diameter by twice the diameter of the cutter being used.
By taking a first cut to form a recess within which an inlay is to be positioned with the guidebushing positioned within the holder lower in the router assembly (and thereby further from the router collet), a relatively larger diameter portion of the sleeve will contact the template, resulting in a relatively smaller recess. Adjustment in the size of the recess may be accomplished by moving the guidebushing further into the holder (and thereby nearer the router collet) to cause a relatively smaller diameter portion of the sleeve to contact the template. In a threaded holder and guidebushing configuration this is accomplished by screwing the guidebushing into the holder. Successive cuts are made following such adjustments until the needed size recess is obtained.
A resilient plug of nylon or other suitable material within the guidebushing engages the holder to create friction between the guidebushing and holder to permit smooth turning of the guidebushing during its adjustment while eliminating the risk of unintended rotation of the guidebushing during use of the apparatus.
Structure may also be provided to facilitate removal of sleeves from the guidebushing. For instance, an annual groove can be formed in the sleeve near its end to facilitate grasping the sleeve. Alternatively an ejector structure can be provided, such as an ejector ring with legs that pass through the guidebushing in order to contact the top side of the sleeve. Such an ejector ring can be used by pressing down on the ring in order to force the legs to in turn force the sleeve down on and off of the guidebushing.